Recent progress on the role of physical modification methods for improving foaming and emulsifying properties of legume proteins

Abstract: Legume seeds have been considered as good resource of plant proteins such as beans, dry peas and lentils. To broaden applications of legume protein in food formulations, it is crucial to enhance their functionalities such as foaming and emulsifying properties. For instance, the abilities of legume proteins to adsorb at oil/water or air/water interfaces are limited due to their compact structure with multiple subunits largely linked through hydrophobic patches. To overcome the abovementioned limitation, a number of simple and mild physical techniques have been developed to modify legume proteins for improving their foaming and emulsifying properties. These include ultrasound, heat treatment and pH shift. In this presentation, pea and bean proteins will be selected as legumin protein representatives. This talk begins with a brief introduction of hierarchical structure of pea and bean protein material to better understand the structure characteristics. It will comprehensive discussed the impact of ultrasound, heat treatment, pH shifts and their combination on protein secondary structure, kinetic adsorption and rheological interfacial properties of pea protein fractions (legumin, vicilin and albumin) and bean protein at interface, and then to research its relationship with foaming and/or emulsifying properties. In general, foaming and emulsifying properties could be improved by means of abovementioned methods because these processing aid irreversibly disrupted the original large micron-sized aggregates in untreated protein samples and change their secondary structure of proteins. For instance, the secondary structure of the protein was changed (e.g., decreased β-sheet content, increased α-helix), the ability of the protein to increase the interfacial pressure (Dπ), and the rates of protein diffusion (K_diff) was increased. Consequently, the emulsifying and foaming capacity was also increased. Our results suggested that protein structure‒function researches are valuable in tailoring proteins for specific functional outcomes and expanding the availability of legumin proteins in variety of food application.